When employing explosives for the purpose of excavation, strip mining, and related earth moving activities, it is common practice to place a number of charges of relatively inexpensive explosive material throughout the area to be affected and use primers for the purposes of exploding all of the various charges. In this way, relatively inexpensive explosive material can be employed for the purposes of effecting the desired heave and movement of the affected area. The primers are high explosive material; however, they are relatively insensitive to normal detonation procedures and require a detonating cap to be initiated. Detonation of the primers initiates the low cost explosive charges. These primers can be initiated by non-electric detonating cord strung throughout the affected area; however, one of the more easily controlled system involved the use of electric blasting caps for the primers. These electric blasting caps are normally cylindrical metal containers or cartridges having a lower portion, or base charge, of high explosive, such as PETN or lead azide. An upper portion of the cartridge includes initiator leads extending from the cartridge. A voltage across the leads causes an abrupt event or eruption of the initiator. In the past, this abrupt event has involved an I.sup.2 R heating of a bridgewire that is directly associated with a sensitive explosive sometimes referred to as a "match head" composition. When this composition or explosive is initiated, the PETN and/or lead azide of the base charge is detonated. This then initiates the primer into which the blasting cap is inserted for the purpose of subsequently initiating the less expensive, bulk type explosive material of the individual charges spaced throughout the affected field. To obtain a delay, a delay explosive is placed between the match head composition and the base charge. This intermediate charge would accurately control the time from the abrupt eruption of the initiator to the explosion of the high explosive base charge. These electric blasting caps are used by the millions throughout the world for the purpose of stringing explosive fields for moving earth in the desired, controlled fashion. Since initiation of the blasting cap is by I.sup.2 R through a bridgewire, a low voltage signal can be employed. This makes the blasting caps susceptible to electronic counter measures (ECM), radio frequency interference (RFI), electromagnetic interference (EMI) and electromagnetic pulses (EMP). Since the low voltages can initiate these blasting caps, stray electric energy, such as lightning, and electrical equipment can induce detonating voltage at the cap wires. This prevented the fields from being strung with caps for a long period of time before detonation.
Since prior blasting caps included a portion of high explosive material, they were classified in a manner which limited their mode of transportation. Also, prior electric blasting caps were somewhat sensitive to impact detonation. These existing caps also were not necessarily nuclear hard due to sensitivity to electromagnetic pulses which could induce a detonation voltage. Further, prior blasting caps sometimes were not insensitive to radar signals. All of these limitations to the use of standard electric blasting caps have been known for some time and had to be taken into consideration in the handling, transportation and use of these blasting caps throughout the world. There has been a tremendous need for an electric blasting cap which is insensitive to the many existing fields and handling vicissitudes associated with the high explosive industry. For this reason, many situations have dictated the abandonment of electric blasting caps for non electric systems. This reduces the control and efficiency of the blasting operation and was a major factor in the limitation of the commercial success of blasting caps.
Many years ago, a detonator known as a "slapper" was suggested using a flat aluminum sheet to drive another plastic sheet known as a "flyer." The theoretical concept was not used in electric blasting caps and did not find use in the explosive art.